Flashcards
Week 11
Cards in this deck (29)
- 1Intervention studiesClinical trial, experimental study. Aim: to select the best available preventative or therapeutic measures to change the natural history of a disease.
- 2Types of intervention studiesTherapeutic (secondary prevention): when someone already has the disease, to see what works. Preventive (primary prevention): prevent initial development of disease
- 3Trial TypesTherapeutic Trials, Preventive trials for healthy individuals and Preventive trials for at risk groups
- 4Clinical trials vs Community trialsClinical trials: e.g. pharmaceutical agencies or research institute, has a specific criteria. Community; has a more rigid criteria e.g. lives in the same area
- 5Efficacy vs. EffectivenessEfficacy; how good a drug is in ideal conditions e.g. clinical trials. Effectiveness; how good a drug works in real conditions e.g. given to a wider population
- 6Design of trials - featuresSampling; sample size and composition. Randomisation; divide subjects b/w groups randomly. Stratification; grouping subs according to charac b4 randomisation. Controls; choosing a good control tx. Cross over; switching tx & control grps after a period of time. Placebo; using to mask what tx is being given. Blinding; assessm. by those unaware of the tx group. (single, double, triple)
- 7Designing intervention studySelection of study population, allocation of intervention, follow up, maintenance & assessment of compliance & Ascertainment of outcomes.
- 8Allocation of study regimesEffect of intervention (tx, procedure or program) should be compared to : another dosage of same drug, another therapy/program, standard medical practice & placebo.
- 9Assignment/AllocationBy random allocation so every individual has the same chance of either group. Purpose: to remove selection bias & groups more comparable
- 10Other allocation methodsNo controls, historical controls (e.g. changes over time), & simultaneous non-randomised controls
- 11Types of clinical trialsRCT, Self controlled designs & cross over designs
- 12Cross over studyUses 2 groups (tx & control), after period tx & placebo withdrawn for washout period (where they receive no tx), the groups swap
- 13Issues in RCT designaim to achieve valid determination of the comparitive benefit of competing interventions for: Prevention, Screening, Tx & Pt management
- 14Content of RCTsPhase I - Clinical pharmacological studies. Phase II - Clinical investigations. Phase III - large scale RCT for effectiveness & safety. Phase IV - Post marketing surveillance
- 15RCT outcomeShould have a single outcome. Secondary outcomes can be examined. Outcomes may be; a continuos variable, a dichotomous (2 outcomes) variable, a time to event variable or QOL.
- 16Who should participate? Phase IIICriteria should be based on those who: have the potential to benefit, have the ability to demonstrate the outcome, are unlikely to show adverse effects, dont have competing risks, are likely to comply & are easy to follow up
- 17Who should participate? Phase IVRecruit a more diverse range of subjects = enhanced external validity & makes the results a better reflection of real life.
- 18Sample sizeFor Phase I and Phase II = small. Phase III = larger and Phase IV = even larger
- 19BindingTo minimalise observation bias. 3 levels: subject, observer & analyst
- 20Time to event studiesPowerful and flexible when outcome variable is appropriate. Suited to long term trials of preventive and screening programs
- 21Group randomised studiesClusters of ppl randomised - suited to community intervention studies. Application: behavioural/lifestyle interventions, infectious diseases interventions, screening trials, health services research. Reduce data collection costs & need larger sample size
- 22Community intervention trialsDefined geographically or socially determined. Advantages: feasibility of delivery of intervention, avoiding contamination between subjects & using site specific resources for delivery
- 23Advantages of RCTsRandomisation balances prognostic factors, Detailed info can be collected on baseline & subsequent charac of subs, Dose lvls pre determined, Blinding reduces bias in assessment of outcome, Assumptions for stat tests met
- 24Disadvantages of RCTsSubject exclusion may limit generalizability of findings to other pts, long period of time req to reach conclusion, large no. of subs may be req, expensive, ethical issues & lack of compliance w/tx
- 25Non-complianceRefusal to take part int he study
- 26Ethical considerationsDont give something harmful, dont deny something beneficial, informed consent & the participant decides.
- 27Exp & cohort studies- analysis & interpretationsimilar analysis, compare risk of the outcome of interest in the exposed (tx grp) and those in the comparison group
- 28AnalysisRR, OR
- 29Issues in interpretationBias potential: from non response, in assessment of outcome, loss to follow up and analytical
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- Epidemiology Flashcards on Week 11, created by Indah on 17/10/2013.
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- Indah
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